This invention relates in general to respirators and in particular to a new and useful apparatus and method for enriching respiratory gas with oxygen.
The invention relates particularly to an apparatus for enriching respiratory gas with oxygen, wherein the entire respiratory gas is taken from an adsorber bed and the enrichment concentration is adjustable by action on the total flow through the adsorber and the portion of the total flow in excess of the consumer flow is removable through an outflow. A similar apparatus is known from German OS No. 28 37 281.
In the known apparatus, the respiratory gas to be enriched with oxygen is conducted through adsorption beds in which the nitrogen is retained and the respiratory gas thus enriched with oxygen can be supplied to the consumer. The proportion of nitrogen retained by the adsorption beds depends essentially on the quantity of gas flowing through the adsorber. With increasing flow the adsorption of nitrogen and hence the enrichment with oxygen decreases. Conversely it follows that at higher amounts of enriched respiratory gas removed by the consumer necessarily the oxygen proportion in the respiratory gas decreases. In a corresponding manner, the oxygen proportion increases when the removal of respiratory gas decreases. Now in the known apparatus the respiratory gas stream enriched with a crrtain oxygen concentration is, as as it leaves the adsorber bed, first collected in a buffer volume. A discharge line is connected to the buffer release and it contains an outflow valve to the atmosphere.
Through the outflow valve a total flow of respiratory gas through the adsorption bed can be adjusted, whereby a certain oxygen concentration in the enriched respiratory gas is established. The buffer volume is connected also, via a control valve, to the consumer line, through which the variable consumption of respiratory gas can be taken from the buffer volume. Thus the oxygen concentration is determined jointly by the variable respiratory gas consumption and the quantity of respiratory gas delivered via the outflow valve. As the quantity taken out of the buffer volume by the consumer changes the enrichment concentration in the respiratory gas mixture also changes.